Some webs show ugly fonts

hi, anyone can help me? i am having problems with lot of webs, the font doesn't look sharp, it looks like semi bold,
i have in windows everything disabled like true type or cr*p like that, because i like sharp fonts in its original way,
however some webs that uses Open sans, looks like return a strange ugly unconfortable view,
i tried installing Open Sans, tried removing all fonts from windows and restarting the computer but looks like nothing helps

I'll unlock the thread but you should also mention your version of Opera.

Note that using non-Truetype fonts is likely to be hard as they only come in certain sizes ... if a site requests a size you don't have then Windows has to scale the font which generally results in something blocky, blurry, or otherwise quite ugly. Some sort of extension to force it to use specific sizes and fonts may be a good idea.